1. Field of the Invention
The present invention relates to an electric connector structure, and more particularly to an image sensor module having an image sensor connected electrically to a printed circuit board.
2. Description of the Related Art
Generally, an image sensor module is configured to photograph a subject using an image sensor, such as a CCD (charge coupled device) or a CMOS that are capable of achieving photoelectric transformation and charge-coupling, to output an electric signal corresponding to the photographed image. The image sensor module includes a printed circuit board (PCB), the image sensor, a device for electrically connecting the PCB to the image sensor, a housing for protecting each of above-mentioned parts, and a lens system for inputting into the image sensor an optical signal embodying the subject.
The image sensor includes the CCD or the CMOS, and converts to an electrical signal an optical signal obtained by photographing the subject. Pixels for converting the optical signal into the electric signal are disposed on an upper surface of the image sensor. Conductive patterns capable of conducting each of electric signals converted by the pixels are formed on the image sensor. These conductive patterns are wire bonded to conductive patterns formed on an upper surface of the PCB, the latter patterns being connected electrically to the image sensor in such a manner so as to detect the electric signal converted by the image sensor and to transmit the electric signal to an exterior.
Methods of manufacturing the above-mentioned image sensor module include a COB (Chip On Board Type) process, a COF (Chip On Film Type) process, and a CSP (Chip Size Package) process.
FIG. 1 is a view showing a conventional COB-type image sensor module, which has an image sensor 120 bonded to an upper surface of a PCB 110. The image sensor 120 includes conductive patterns 122 and a pixel 121 for detecting radiated light, and is bonded to an upper center portion of the PCB 110, on which the conductive patterns 111 are formed, by a die bonder. The image sensor 120 is electrically connected to the conductive patterns 111 formed on the PCB 110 by a wire bonding 160, and is protected by a housing 150 mounted on the PCB 110.
An infrared cut-off filter 130 is fixed to an upper portion of the housing 150 in opposition to the image sensor 120. Also, a lens system 140 is fixed to the infrared cut-off filter 130 in order to converge light radiated into the image sensor 120.
However, the above-mentioned COB-type image sensor module has a problem in that the pixel of the image sensor is easily contaminated by impurities.
FIG. 2 is a view showing a conventional COF-type image sensor module. Referring to FIG. 2, the COF-type image sensor module has an image sensor 220 affixed to a lower portion of a PCB 210, which is formed at a center portion thereof with a hole 212, through an ACF (Anisotropic Conductive Film). The ACF includes a conductive ball and is melted when pressure or heat is applied thereto, in such a manner that the image sensor 220 is electrically bonded to the PCB 210.
The image sensor 220 has conductive patterns 222 and a pixel 221 at one side, and is bonded to the PCB 210 in such a manner that the pixel faces a hole 212 of the PCB. Conductive patterns 211 formed on the PCB 210 are adhered by the conductive pattern 222 of the image sensor 220 and the conductive ball 230.
A cap-type housing 260 is mounted on an upper surface of the PCB 210, and fixes an infrared cut-off filter 240 located at an upper portion of the housing. The lens system 250 is set on an upper portion of the housing 260 opposed to the pixel 221 and aligned with the infrared cut-off filter 240 so as to guide radiated light into the pixel.
However, the image sensor is likewise easily contaminated by impurities, and the COF-type image sensor module has a further problem in that the bonding force of the ACF varies widely in dependence on temperature.
FIG. 3 is a view showing a conventional CSP-type image sensor module. Referring to FIG. 3, the CSP-type image sensor module includes an image sensor 320, which is formed at an upper surface thereof with a pixel 321 and is formed at a lower surface thereof with conductive patterns 322 electrically connected to the pixel 321. In addition, a glass substrate 370 is bonded to the upper surface of the image sensor 320 so as to enclose the pixel 321, thereby preventing the pixel from being contaminated by impurities.
The image sensor 320 is bonded to an upper surface of a PCB 310, which is formed at the upper surface thereof with conductive patterns 311, by an oven reflow process.
Namely, a solder ball (not shown) is inserted between the PCB 310 and the image sensor 320, and is melted through the oven reflow process, thereby electrically bonding the image sensor 320 to the PCB 310.
The above-mentioned CSP-type image sensor module includes a housing mounted on the PCB 310, an infrared cut-off filter 330 fixed to an upper portion of the housing 350, and a lens system 340.
Problematically, however, processes are required for connecting the pixel of the image sensor to the conductive patterns and for bonding the glass substrate to an upper surface of the image sensor, because the pixel and conductive patterns are formed on upper and lower surfaces of the image sensor. These additional process steps drive up manufacturing cost because of the increased number of steps and parts required.